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<h1 id="sec_name">
<span data-if="hdevelop" style="display:inline;">lines_facet</span><span data-if="c" style="display:none;">lines_facet</span><span data-if="cpp" style="display:none;">LinesFacet</span><span data-if="dotnet" style="display:none;">LinesFacet</span><span data-if="python" style="display:none;">lines_facet</span> (算子名称)</h1>
<h2>名称</h2>
<p><code><span data-if="hdevelop" style="display:inline;">lines_facet</span><span data-if="c" style="display:none;">lines_facet</span><span data-if="cpp" style="display:none;">LinesFacet</span><span data-if="dotnet" style="display:none;">LinesFacet</span><span data-if="python" style="display:none;">lines_facet</span></code> — Detection of lines using the facet model.</p>
<h2 id="sec_synopsis">参数签名</h2>
<div data-if="hdevelop" style="display:inline;">
<p>
<code><b>lines_facet</b>(<a href="#Image"><i>Image</i></a> : <a href="#Lines"><i>Lines</i></a> : <a href="#MaskSize"><i>MaskSize</i></a>, <a href="#Low"><i>Low</i></a>, <a href="#High"><i>High</i></a>, <a href="#LightDark"><i>LightDark</i></a> : )</code></p>
</div>
<div data-if="c" style="display:none;">
<p>
<code>Herror <b>lines_facet</b>(const Hobject <a href="#Image"><i>Image</i></a>, Hobject* <a href="#Lines"><i>Lines</i></a>, const Hlong <a href="#MaskSize"><i>MaskSize</i></a>, double <a href="#Low"><i>Low</i></a>, double <a href="#High"><i>High</i></a>, const char* <a href="#LightDark"><i>LightDark</i></a>)</code></p>
<p>
<code>Herror <b>T_lines_facet</b>(const Hobject <a href="#Image"><i>Image</i></a>, Hobject* <a href="#Lines"><i>Lines</i></a>, const Htuple <a href="#MaskSize"><i>MaskSize</i></a>, const Htuple <a href="#Low"><i>Low</i></a>, const Htuple <a href="#High"><i>High</i></a>, const Htuple <a href="#LightDark"><i>LightDark</i></a>)</code></p>
</div>
<div data-if="cpp" style="display:none;">
<p>
<code>void <b>LinesFacet</b>(const HObject&amp; <a href="#Image"><i>Image</i></a>, HObject* <a href="#Lines"><i>Lines</i></a>, const HTuple&amp; <a href="#MaskSize"><i>MaskSize</i></a>, const HTuple&amp; <a href="#Low"><i>Low</i></a>, const HTuple&amp; <a href="#High"><i>High</i></a>, const HTuple&amp; <a href="#LightDark"><i>LightDark</i></a>)</code></p>
<p>
<code><a href="HXLDCont.html">HXLDCont</a> <a href="HImage.html">HImage</a>::<b>LinesFacet</b>(Hlong <a href="#MaskSize"><i>MaskSize</i></a>, const HTuple&amp; <a href="#Low"><i>Low</i></a>, const HTuple&amp; <a href="#High"><i>High</i></a>, const HString&amp; <a href="#LightDark"><i>LightDark</i></a>) const</code></p>
<p>
<code><a href="HXLDCont.html">HXLDCont</a> <a href="HImage.html">HImage</a>::<b>LinesFacet</b>(Hlong <a href="#MaskSize"><i>MaskSize</i></a>, double <a href="#Low"><i>Low</i></a>, double <a href="#High"><i>High</i></a>, const HString&amp; <a href="#LightDark"><i>LightDark</i></a>) const</code></p>
<p>
<code><a href="HXLDCont.html">HXLDCont</a> <a href="HImage.html">HImage</a>::<b>LinesFacet</b>(Hlong <a href="#MaskSize"><i>MaskSize</i></a>, double <a href="#Low"><i>Low</i></a>, double <a href="#High"><i>High</i></a>, const char* <a href="#LightDark"><i>LightDark</i></a>) const</code></p>
<p>
<code><a href="HXLDCont.html">HXLDCont</a> <a href="HImage.html">HImage</a>::<b>LinesFacet</b>(Hlong <a href="#MaskSize"><i>MaskSize</i></a>, double <a href="#Low"><i>Low</i></a>, double <a href="#High"><i>High</i></a>, const wchar_t* <a href="#LightDark"><i>LightDark</i></a>) const  <span class="signnote">
            (
            Windows only)
          </span></code></p>
</div>
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<p>
<code>static void <a href="HOperatorSet.html">HOperatorSet</a>.<b>LinesFacet</b>(<a href="HObject.html">HObject</a> <a href="#Image"><i>image</i></a>, out <a href="HObject.html">HObject</a> <a href="#Lines"><i>lines</i></a>, <a href="HTuple.html">HTuple</a> <a href="#MaskSize"><i>maskSize</i></a>, <a href="HTuple.html">HTuple</a> <a href="#Low"><i>low</i></a>, <a href="HTuple.html">HTuple</a> <a href="#High"><i>high</i></a>, <a href="HTuple.html">HTuple</a> <a href="#LightDark"><i>lightDark</i></a>)</code></p>
<p>
<code><a href="HXLDCont.html">HXLDCont</a> <a href="HImage.html">HImage</a>.<b>LinesFacet</b>(int <a href="#MaskSize"><i>maskSize</i></a>, <a href="HTuple.html">HTuple</a> <a href="#Low"><i>low</i></a>, <a href="HTuple.html">HTuple</a> <a href="#High"><i>high</i></a>, string <a href="#LightDark"><i>lightDark</i></a>)</code></p>
<p>
<code><a href="HXLDCont.html">HXLDCont</a> <a href="HImage.html">HImage</a>.<b>LinesFacet</b>(int <a href="#MaskSize"><i>maskSize</i></a>, double <a href="#Low"><i>low</i></a>, double <a href="#High"><i>high</i></a>, string <a href="#LightDark"><i>lightDark</i></a>)</code></p>
</div>
<div data-if="python" style="display:none;">
<p>
<code>def <b>lines_facet</b>(<a href="#Image"><i>image</i></a>: HObject, <a href="#MaskSize"><i>mask_size</i></a>: int, <a href="#Low"><i>low</i></a>: Union[float, int], <a href="#High"><i>high</i></a>: Union[float, int], <a href="#LightDark"><i>light_dark</i></a>: str) -&gt; HObject</code></p>
</div>
<h2 id="sec_description">描述</h2>
<p>该算子 <code><span data-if="hdevelop" style="display:inline">lines_facet</span><span data-if="c" style="display:none">lines_facet</span><span data-if="cpp" style="display:none">LinesFacet</span><span data-if="com" style="display:none">LinesFacet</span><span data-if="dotnet" style="display:none">LinesFacet</span><span data-if="python" style="display:none">lines_facet</span></code> can be used to extract lines
(curvilinear structures) from the image <a href="#Image"><i><code><span data-if="hdevelop" style="display:inline">Image</span><span data-if="c" style="display:none">Image</span><span data-if="cpp" style="display:none">Image</span><span data-if="com" style="display:none">Image</span><span data-if="dotnet" style="display:none">image</span><span data-if="python" style="display:none">image</span></code></i></a>.  The
extracted lines are returned in <a href="#Lines"><i><code><span data-if="hdevelop" style="display:inline">Lines</span><span data-if="c" style="display:none">Lines</span><span data-if="cpp" style="display:none">Lines</span><span data-if="com" style="display:none">Lines</span><span data-if="dotnet" style="display:none">lines</span><span data-if="python" style="display:none">lines</span></code></i></a> as subpixel
precise XLD-contours.  The parameter <a href="#LightDark"><i><code><span data-if="hdevelop" style="display:inline">LightDark</span><span data-if="c" style="display:none">LightDark</span><span data-if="cpp" style="display:none">LightDark</span><span data-if="com" style="display:none">LightDark</span><span data-if="dotnet" style="display:none">lightDark</span><span data-if="python" style="display:none">light_dark</span></code></i></a>
determines, whether bright or dark lines are extracted.
</p>
<p>The extraction is done by using the facet model, i.e., a least
squares fit, to determine the parameters of a quadratic polynomial
in x and y for each point of the image.  The parameter
<a href="#MaskSize"><i><code><span data-if="hdevelop" style="display:inline">MaskSize</span><span data-if="c" style="display:none">MaskSize</span><span data-if="cpp" style="display:none">MaskSize</span><span data-if="com" style="display:none">MaskSize</span><span data-if="dotnet" style="display:none">maskSize</span><span data-if="python" style="display:none">mask_size</span></code></i></a> determines the size of the window used for the
least squares fit.  Larger values of <a href="#MaskSize"><i><code><span data-if="hdevelop" style="display:inline">MaskSize</span><span data-if="c" style="display:none">MaskSize</span><span data-if="cpp" style="display:none">MaskSize</span><span data-if="com" style="display:none">MaskSize</span><span data-if="dotnet" style="display:none">maskSize</span><span data-if="python" style="display:none">mask_size</span></code></i></a> lead to a
larger smoothing of the image, but can lead to worse localization of
the line.  The parameters of the polynomial are used to calculate
the line direction for each pixel.  Pixels which exhibit a local
maximum in the second directional derivative perpendicular to the
line direction are marked as line points.  The line points found in
this manner are then linked to contours.  This is done by
immediately accepting line points that have a second derivative
larger than <a href="#High"><i><code><span data-if="hdevelop" style="display:inline">High</span><span data-if="c" style="display:none">High</span><span data-if="cpp" style="display:none">High</span><span data-if="com" style="display:none">High</span><span data-if="dotnet" style="display:none">high</span><span data-if="python" style="display:none">high</span></code></i></a>.  Points that have a second derivative
smaller than <a href="#Low"><i><code><span data-if="hdevelop" style="display:inline">Low</span><span data-if="c" style="display:none">Low</span><span data-if="cpp" style="display:none">Low</span><span data-if="com" style="display:none">Low</span><span data-if="dotnet" style="display:none">low</span><span data-if="python" style="display:none">low</span></code></i></a> are rejected.  All other line points are
accepted if they are connected to accepted points by a connected
path.  This is similar to a hysteresis threshold operation with
infinite path length (see <a href="hysteresis_threshold.html"><code><span data-if="hdevelop" style="display:inline">hysteresis_threshold</span><span data-if="c" style="display:none">hysteresis_threshold</span><span data-if="cpp" style="display:none">HysteresisThreshold</span><span data-if="com" style="display:none">HysteresisThreshold</span><span data-if="dotnet" style="display:none">HysteresisThreshold</span><span data-if="python" style="display:none">hysteresis_threshold</span></code></a>).
However, this function is not used internally since it does not
allow the extraction of subpixel precise contours.
</p>
<p>The gist of how to select the thresholds in the description of
<a href="lines_gauss.html"><code><span data-if="hdevelop" style="display:inline">lines_gauss</span><span data-if="c" style="display:none">lines_gauss</span><span data-if="cpp" style="display:none">LinesGauss</span><span data-if="com" style="display:none">LinesGauss</span><span data-if="dotnet" style="display:none">LinesGauss</span><span data-if="python" style="display:none">lines_gauss</span></code></a> also holds for this operator.  A value of
Sigma = 1.5 there roughly corresponds to a <a href="#MaskSize"><i><code><span data-if="hdevelop" style="display:inline">MaskSize</span><span data-if="c" style="display:none">MaskSize</span><span data-if="cpp" style="display:none">MaskSize</span><span data-if="com" style="display:none">MaskSize</span><span data-if="dotnet" style="display:none">maskSize</span><span data-if="python" style="display:none">mask_size</span></code></i></a> of 5
here.
</p>
<p>The extracted lines are returned in a topologically sound data
structure in <a href="#Lines"><i><code><span data-if="hdevelop" style="display:inline">Lines</span><span data-if="c" style="display:none">Lines</span><span data-if="cpp" style="display:none">Lines</span><span data-if="com" style="display:none">Lines</span><span data-if="dotnet" style="display:none">lines</span><span data-if="python" style="display:none">lines</span></code></i></a>.  This means that lines are correctly
split at junction points.
</p>
<p><code><span data-if="hdevelop" style="display:inline">lines_facet</span><span data-if="c" style="display:none">lines_facet</span><span data-if="cpp" style="display:none">LinesFacet</span><span data-if="com" style="display:none">LinesFacet</span><span data-if="dotnet" style="display:none">LinesFacet</span><span data-if="python" style="display:none">lines_facet</span></code> defines the following attributes for each
line point:
</p>
<dl class="generic">

<dt><b><i><span data-if="hdevelop" style="display:inline">'angle'</span><span data-if="c" style="display:none">"angle"</span><span data-if="cpp" style="display:none">"angle"</span><span data-if="com" style="display:none">"angle"</span><span data-if="dotnet" style="display:none">"angle"</span><span data-if="python" style="display:none">"angle"</span></i>:</b></dt>
<dd><p>
    The angle of the direction perpendicular
to the line
</p></dd>

<dt><b><i><span data-if="hdevelop" style="display:inline">'response'</span><span data-if="c" style="display:none">"response"</span><span data-if="cpp" style="display:none">"response"</span><span data-if="com" style="display:none">"response"</span><span data-if="dotnet" style="display:none">"response"</span><span data-if="python" style="display:none">"response"</span></i>:</b></dt>
<dd><p>
 The magnitude of the second derivative
</p></dd>
</dl>
<p>Use <a href="get_contour_attrib_xld.html"><code><span data-if="hdevelop" style="display:inline">get_contour_attrib_xld</span><span data-if="c" style="display:none">get_contour_attrib_xld</span><span data-if="cpp" style="display:none">GetContourAttribXld</span><span data-if="com" style="display:none">GetContourAttribXld</span><span data-if="dotnet" style="display:none">GetContourAttribXld</span><span data-if="python" style="display:none">get_contour_attrib_xld</span></code></a> to obtain attribute values.
See 该算子 reference of <a href="get_contour_attrib_xld.html"><code><span data-if="hdevelop" style="display:inline">get_contour_attrib_xld</span><span data-if="c" style="display:none">get_contour_attrib_xld</span><span data-if="cpp" style="display:none">GetContourAttribXld</span><span data-if="com" style="display:none">GetContourAttribXld</span><span data-if="dotnet" style="display:none">GetContourAttribXld</span><span data-if="python" style="display:none">get_contour_attrib_xld</span></code></a> for further
information about contour attributes.
</p>
<h2 id="sec_attention">注意</h2>
<p>The smaller the filter size <a href="#MaskSize"><i><code><span data-if="hdevelop" style="display:inline">MaskSize</span><span data-if="c" style="display:none">MaskSize</span><span data-if="cpp" style="display:none">MaskSize</span><span data-if="com" style="display:none">MaskSize</span><span data-if="dotnet" style="display:none">maskSize</span><span data-if="python" style="display:none">mask_size</span></code></i></a> is chosen, the more
short, fragmented lines will be extracted.  This can lead to
considerably longer execution times.
</p>
<p>Note that filter operators may return unexpected results if
an image with a reduced domain is used as input. Please refer to the
chapter <a href="toc_filters.html">过滤器</a>.</p>
<h2 id="sec_execution">运行信息</h2>
<ul>
  <li>多线程类型:可重入(与非独占操作符并行运行)。</li>
<li>多线程作用域:全局(可以从任何线程调用)。</li>
  
    <li>Automatically parallelized on internal data level.</li>
  
</ul>
<h2 id="sec_parameters">参数表</h2>
  <div class="par">
<div class="parhead">
<span id="Image" class="parname"><b><code><span data-if="hdevelop" style="display:inline">Image</span><span data-if="c" style="display:none">Image</span><span data-if="cpp" style="display:none">Image</span><span data-if="com" style="display:none">Image</span><span data-if="dotnet" style="display:none">image</span><span data-if="python" style="display:none">image</span></code></b> (input_object)  </span><span>singlechannelimage <code>→</code> <span data-if="hdevelop" style="display:inline">object</span><span data-if="dotnet" style="display:none"><a href="HImage.html">HImage</a></span><span data-if="python" style="display:none">HObject</span><span data-if="cpp" style="display:none"><a href="HImage.html">HImage</a></span><span data-if="c" style="display:none">Hobject</span> (byte / int1 / int2 / uint2 / int4 / real)</span>
</div>
<p class="pardesc">Input image.</p>
</div>
  <div class="par">
<div class="parhead">
<span id="Lines" class="parname"><b><code><span data-if="hdevelop" style="display:inline">Lines</span><span data-if="c" style="display:none">Lines</span><span data-if="cpp" style="display:none">Lines</span><span data-if="com" style="display:none">Lines</span><span data-if="dotnet" style="display:none">lines</span><span data-if="python" style="display:none">lines</span></code></b> (output_object)  </span><span>xld_cont-array <code>→</code> <span data-if="hdevelop" style="display:inline">object</span><span data-if="dotnet" style="display:none"><a href="HXLDCont.html">HXLDCont</a></span><span data-if="python" style="display:none">HObject</span><span data-if="cpp" style="display:none"><a href="HXLDCont.html">HXLDCont</a></span><span data-if="c" style="display:none">Hobject *</span></span>
</div>
<p class="pardesc">Extracted lines.</p>
</div>
  <div class="par">
<div class="parhead">
<span id="MaskSize" class="parname"><b><code><span data-if="hdevelop" style="display:inline">MaskSize</span><span data-if="c" style="display:none">MaskSize</span><span data-if="cpp" style="display:none">MaskSize</span><span data-if="com" style="display:none">MaskSize</span><span data-if="dotnet" style="display:none">maskSize</span><span data-if="python" style="display:none">mask_size</span></code></b> (input_control)  </span><span>integer <code>→</code> <span data-if="dotnet" style="display:none"><a href="HTuple.html">HTuple</a></span><span data-if="python" style="display:none">int</span><span data-if="cpp" style="display:none"><a href="HTuple.html">HTuple</a></span><span data-if="c" style="display:none">Htuple</span><span data-if="hdevelop" style="display:inline"> (integer)</span><span data-if="dotnet" style="display:none"> (<i>int</i> / </span><span data-if="dotnet" style="display:none">long)</span><span data-if="cpp" style="display:none"> (<i>Hlong</i>)</span><span data-if="c" style="display:none"> (<i>Hlong</i>)</span></span>
</div>
<p class="pardesc">Size of the facet model mask.</p>
<p class="pardesc"><span class="parcat">Default:
      </span>5</p>
<p class="pardesc"><span class="parcat">List of values:
      </span>3, 5, 7, 9, 11</p>
</div>
  <div class="par">
<div class="parhead">
<span id="Low" class="parname"><b><code><span data-if="hdevelop" style="display:inline">Low</span><span data-if="c" style="display:none">Low</span><span data-if="cpp" style="display:none">Low</span><span data-if="com" style="display:none">Low</span><span data-if="dotnet" style="display:none">low</span><span data-if="python" style="display:none">low</span></code></b> (input_control)  </span><span>number <code>→</code> <span data-if="dotnet" style="display:none"><a href="HTuple.html">HTuple</a></span><span data-if="python" style="display:none">Union[float, int]</span><span data-if="cpp" style="display:none"><a href="HTuple.html">HTuple</a></span><span data-if="c" style="display:none">Htuple</span><span data-if="hdevelop" style="display:inline"> (real / </span><span data-if="hdevelop" style="display:inline">integer)</span><span data-if="dotnet" style="display:none"> (<i>double</i> / </span><span data-if="dotnet" style="display:none">int / </span><span data-if="dotnet" style="display:none">long)</span><span data-if="cpp" style="display:none"> (<i>double</i> / </span><span data-if="cpp" style="display:none">Hlong)</span><span data-if="c" style="display:none"> (<i>double</i> / </span><span data-if="c" style="display:none">Hlong)</span></span>
</div>
<p class="pardesc">Lower threshold for the hysteresis threshold
operation.</p>
<p class="pardesc"><span class="parcat">Default:
      </span>3</p>
<p class="pardesc"><span class="parcat">Suggested values:
      </span>0, 0.5, 1, 2, 3, 4, 5, 8, 10</p>
<p class="pardesc"><span class="parcat">Value range:
      </span><code>0
          ≤
        
    <span data-if="hdevelop" style="display:inline">Low</span>
    <span data-if="c" style="display:none">Low</span>
    <span data-if="cpp" style="display:none">Low</span>
    <span data-if="com" style="display:none">Low</span>
    <span data-if="dotnet" style="display:none">low</span>
    <span data-if="python" style="display:none">low</span>
    </code></p>
<p class="pardesc"><span class="parcat">Recommended increment:
      </span>0.5</p>
</div>
  <div class="par">
<div class="parhead">
<span id="High" class="parname"><b><code><span data-if="hdevelop" style="display:inline">High</span><span data-if="c" style="display:none">High</span><span data-if="cpp" style="display:none">High</span><span data-if="com" style="display:none">High</span><span data-if="dotnet" style="display:none">high</span><span data-if="python" style="display:none">high</span></code></b> (input_control)  </span><span>number <code>→</code> <span data-if="dotnet" style="display:none"><a href="HTuple.html">HTuple</a></span><span data-if="python" style="display:none">Union[float, int]</span><span data-if="cpp" style="display:none"><a href="HTuple.html">HTuple</a></span><span data-if="c" style="display:none">Htuple</span><span data-if="hdevelop" style="display:inline"> (real / </span><span data-if="hdevelop" style="display:inline">integer)</span><span data-if="dotnet" style="display:none"> (<i>double</i> / </span><span data-if="dotnet" style="display:none">int / </span><span data-if="dotnet" style="display:none">long)</span><span data-if="cpp" style="display:none"> (<i>double</i> / </span><span data-if="cpp" style="display:none">Hlong)</span><span data-if="c" style="display:none"> (<i>double</i> / </span><span data-if="c" style="display:none">Hlong)</span></span>
</div>
<p class="pardesc">Upper threshold for the hysteresis threshold
operation.</p>
<p class="pardesc"><span class="parcat">Default:
      </span>8</p>
<p class="pardesc"><span class="parcat">Suggested values:
      </span>0, 0.5, 1, 2, 3, 4, 5, 8, 10, 12, 15, 18, 20, 25</p>
<p class="pardesc"><span class="parcat">Value range:
      </span><code>0
          ≤
        
    <span data-if="hdevelop" style="display:inline">High</span>
    <span data-if="c" style="display:none">High</span>
    <span data-if="cpp" style="display:none">High</span>
    <span data-if="com" style="display:none">High</span>
    <span data-if="dotnet" style="display:none">high</span>
    <span data-if="python" style="display:none">high</span>
    </code></p>
<p class="pardesc"><span class="parcat">Recommended increment:
      </span>0.5</p>
<p class="pardesc"><span class="parcat">Restriction:
      </span><code>High &gt;= Low</code></p>
</div>
  <div class="par">
<div class="parhead">
<span id="LightDark" class="parname"><b><code><span data-if="hdevelop" style="display:inline">LightDark</span><span data-if="c" style="display:none">LightDark</span><span data-if="cpp" style="display:none">LightDark</span><span data-if="com" style="display:none">LightDark</span><span data-if="dotnet" style="display:none">lightDark</span><span data-if="python" style="display:none">light_dark</span></code></b> (input_control)  </span><span>string <code>→</code> <span data-if="dotnet" style="display:none"><a href="HTuple.html">HTuple</a></span><span data-if="python" style="display:none">str</span><span data-if="cpp" style="display:none"><a href="HTuple.html">HTuple</a></span><span data-if="c" style="display:none">Htuple</span><span data-if="hdevelop" style="display:inline"> (string)</span><span data-if="dotnet" style="display:none"> (<i>string</i>)</span><span data-if="cpp" style="display:none"> (<i>HString</i>)</span><span data-if="c" style="display:none"> (<i>char*</i>)</span></span>
</div>
<p class="pardesc">Extract bright or dark lines.</p>
<p class="pardesc"><span class="parcat">Default:
      </span>
    <span data-if="hdevelop" style="display:inline">'light'</span>
    <span data-if="c" style="display:none">"light"</span>
    <span data-if="cpp" style="display:none">"light"</span>
    <span data-if="com" style="display:none">"light"</span>
    <span data-if="dotnet" style="display:none">"light"</span>
    <span data-if="python" style="display:none">"light"</span>
</p>
<p class="pardesc"><span class="parcat">List of values:
      </span><span data-if="hdevelop" style="display:inline">'dark'</span><span data-if="c" style="display:none">"dark"</span><span data-if="cpp" style="display:none">"dark"</span><span data-if="com" style="display:none">"dark"</span><span data-if="dotnet" style="display:none">"dark"</span><span data-if="python" style="display:none">"dark"</span>, <span data-if="hdevelop" style="display:inline">'light'</span><span data-if="c" style="display:none">"light"</span><span data-if="cpp" style="display:none">"light"</span><span data-if="com" style="display:none">"light"</span><span data-if="dotnet" style="display:none">"light"</span><span data-if="python" style="display:none">"light"</span></p>
</div>
<div data-if="hdevelop" style="display:inline">
<h2 id="sec_example_hdevelop">例程 (HDevelop)</h2>
<pre class="example">
* Detection of lines in an aerial image
read_image(Image,'mreut4_3')
lines_facet(Image,Lines,5,3,8,'light')
dev_display(Lines)
</pre>
</div>
<div data-if="c" style="display:none">
<h2 id="sec_example_c">例程 (C)</h2>
<pre class="example">
/* Detection of lines in an aerial image */
read_image(&amp;Image,"mreut4_3");
lines_facet(Image:&amp;Lines:5,3,8,"light");
disp_xld(Lines,WindowHandle);</pre>
</div>
<div data-if="cpp" style="display:none">
<h2 id="sec_example_cpp">例程 (HDevelop)</h2>
<pre class="example">
* Detection of lines in an aerial image
read_image(Image,'mreut4_3')
lines_facet(Image,Lines,5,3,8,'light')
dev_display(Lines)
</pre>
</div>
<div data-if="com" style="display:none">
<h2 id="sec_example_com">例程 (HDevelop)</h2>
<pre class="example">
* Detection of lines in an aerial image
read_image(Image,'mreut4_3')
lines_facet(Image,Lines,5,3,8,'light')
dev_display(Lines)
</pre>
</div>
<div data-if="dotnet" style="display:none">
<h2 id="sec_example_dotnet">例程 (HDevelop)</h2>
<pre class="example">
* Detection of lines in an aerial image
read_image(Image,'mreut4_3')
lines_facet(Image,Lines,5,3,8,'light')
dev_display(Lines)
</pre>
</div>
<h2 id="sec_complexity">Complexity</h2>
<p>Let A be the number of pixels in the domain of <a href="#Image"><i><code><span data-if="hdevelop" style="display:inline">Image</span><span data-if="c" style="display:none">Image</span><span data-if="cpp" style="display:none">Image</span><span data-if="com" style="display:none">Image</span><span data-if="dotnet" style="display:none">image</span><span data-if="python" style="display:none">image</span></code></i></a>.
Then the runtime complexity is O(A*<a href="#MaskSize"><i><code><span data-if="hdevelop" style="display:inline">MaskSize</span><span data-if="c" style="display:none">MaskSize</span><span data-if="cpp" style="display:none">MaskSize</span><span data-if="com" style="display:none">MaskSize</span><span data-if="dotnet" style="display:none">maskSize</span><span data-if="python" style="display:none">mask_size</span></code></i></a>).
</p>
<p>The amount of temporary memory required is dependent on the height H
of the domain of <a href="#Image"><i><code><span data-if="hdevelop" style="display:inline">Image</span><span data-if="c" style="display:none">Image</span><span data-if="cpp" style="display:none">Image</span><span data-if="com" style="display:none">Image</span><span data-if="dotnet" style="display:none">image</span><span data-if="python" style="display:none">image</span></code></i></a> and the width W of <a href="#Image"><i><code><span data-if="hdevelop" style="display:inline">Image</span><span data-if="c" style="display:none">Image</span><span data-if="cpp" style="display:none">Image</span><span data-if="com" style="display:none">Image</span><span data-if="dotnet" style="display:none">image</span><span data-if="python" style="display:none">image</span></code></i></a>.
Let S = W*H, then <code><span data-if="hdevelop" style="display:inline">lines_facet</span><span data-if="c" style="display:none">lines_facet</span><span data-if="cpp" style="display:none">LinesFacet</span><span data-if="com" style="display:none">LinesFacet</span><span data-if="dotnet" style="display:none">LinesFacet</span><span data-if="python" style="display:none">lines_facet</span></code> requires at least 55*S
bytes of temporary memory during execution.</p>
<h2 id="sec_result">结果</h2>
<p><code><span data-if="hdevelop" style="display:inline">lines_facet</span><span data-if="c" style="display:none">lines_facet</span><span data-if="cpp" style="display:none">LinesFacet</span><span data-if="com" style="display:none">LinesFacet</span><span data-if="dotnet" style="display:none">LinesFacet</span><span data-if="python" style="display:none">lines_facet</span></code> returns <TT>2</TT> (
      <TT>H_MSG_TRUE</TT>)
     if all parameters are correct
and no error occurs during execution.  If the input is empty the
behavior can be set via
<a href="set_system.html"><code><span data-if="hdevelop" style="display:inline">set_system(::'no_object_result',&lt;Result&gt;:)</span><span data-if="c" style="display:none">set_system("no_object_result",&lt;Result&gt;)</span><span data-if="cpp" style="display:none">SetSystem("no_object_result",&lt;Result&gt;)</span><span data-if="com" style="display:none">SetSystem("no_object_result",&lt;Result&gt;)</span><span data-if="dotnet" style="display:none">SetSystem("no_object_result",&lt;Result&gt;)</span><span data-if="python" style="display:none">set_system("no_object_result",&lt;Result&gt;)</span></code></a>.  If
necessary, an exception is raised.</p>
<h2 id="sec_successors">可能的后置算子</h2>
<p>
<code><a href="gen_polygons_xld.html"><span data-if="hdevelop" style="display:inline">gen_polygons_xld</span><span data-if="c" style="display:none">gen_polygons_xld</span><span data-if="cpp" style="display:none">GenPolygonsXld</span><span data-if="com" style="display:none">GenPolygonsXld</span><span data-if="dotnet" style="display:none">GenPolygonsXld</span><span data-if="python" style="display:none">gen_polygons_xld</span></a></code>
</p>
<h2 id="sec_alternatives">可替代算子</h2>
<p>
<code><a href="lines_gauss.html"><span data-if="hdevelop" style="display:inline">lines_gauss</span><span data-if="c" style="display:none">lines_gauss</span><span data-if="cpp" style="display:none">LinesGauss</span><span data-if="com" style="display:none">LinesGauss</span><span data-if="dotnet" style="display:none">LinesGauss</span><span data-if="python" style="display:none">lines_gauss</span></a></code>
</p>
<h2 id="sec_see">参考其它</h2>
<p>
<code><a href="bandpass_image.html"><span data-if="hdevelop" style="display:inline">bandpass_image</span><span data-if="c" style="display:none">bandpass_image</span><span data-if="cpp" style="display:none">BandpassImage</span><span data-if="com" style="display:none">BandpassImage</span><span data-if="dotnet" style="display:none">BandpassImage</span><span data-if="python" style="display:none">bandpass_image</span></a></code>, 
<code><a href="dyn_threshold.html"><span data-if="hdevelop" style="display:inline">dyn_threshold</span><span data-if="c" style="display:none">dyn_threshold</span><span data-if="cpp" style="display:none">DynThreshold</span><span data-if="com" style="display:none">DynThreshold</span><span data-if="dotnet" style="display:none">DynThreshold</span><span data-if="python" style="display:none">dyn_threshold</span></a></code>, 
<code><a href="topographic_sketch.html"><span data-if="hdevelop" style="display:inline">topographic_sketch</span><span data-if="c" style="display:none">topographic_sketch</span><span data-if="cpp" style="display:none">TopographicSketch</span><span data-if="com" style="display:none">TopographicSketch</span><span data-if="dotnet" style="display:none">TopographicSketch</span><span data-if="python" style="display:none">topographic_sketch</span></a></code>
</p>
<h2 id="sec_references">References</h2>
<p>

A. Busch: “Fast Recognition of Lines in Digital Images Without
User-Supplied Parameters”. In H. Ebner, C. Heipke, K.Eder, eds.,
“Spatial Information from Digital Photogrammetry and Computer
Vision”, International Archives of Photogrammetry and Remote
Sensing, Vol. 30, Part 3/1, pp. 91-97, 1994.
</p>
<h2 id="sec_module">模块</h2>
<p>
2D 度量</p>
<!--OP_REF_FOOTER_START-->
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